Photovoltaic roofing elements

ABSTRACT

The present invention relates generally to the photovoltaic generation of electrical energy. The present invention relates more particularly to photovoltaic roofing products for use in photovoltaically generating electrical energy. One aspect of the invention is a photovoltaic roofing element including a roofing substrate; a photovoltaic element disposed on the roofing substrate; an electrical connector operatively connected to the photovoltaic element, the electrical connector having a top side, a down-roof side and an electrical terminus; and a shield disposed adjacent the electrical terminus of the electrical connector on its down-roof side, its top side, or both.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application Ser. No. 61/238,566, filed Aug. 31, 2009,which is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the photovoltaic generationof electrical energy. The present invention relates more particularly tophotovoltaic roofing products for use in photovoltaically generatingelectrical energy.

2. Technical Background

The search for alternative sources of energy has been motivated by atleast two factors. First, fossil fuels have become increasinglyexpensive due to increasing scarcity and unrest in areas rich inpetroleum deposits. Second, there exists overwhelming concern about theeffects of the combustion of fossil fuels on the environment due tofactors such as air pollution (from NO_(x), hydrocarbons and ozone) andglobal warming (from CO₂). In recent years, research and developmentattention has focused on harvesting energy from natural environmentalsources such as wind, flowing water, and the sun. Of the three, the sunappears to be the most widely useful energy source across thecontinental United States; most locales get enough sunshine to makesolar energy feasible.

Accordingly, there are now available components that convert lightenergy into electrical energy. Such “photovoltaic cells” are often madefrom semiconductor-type materials such as doped silicon in either singlecrystalline, polycrystalline, or amorphous form. The use of photovoltaiccells on roofs is becoming increasingly common, especially as systemperformance has improved. They can be used, for example, to provide atleast a significant fraction of the electrical energy needed for abuilding's overall function: or they can be used to power one or moreparticular devices, such as exterior lighting systems and well pumps.

Accordingly, research and development attention has turned towardintegrating photovoltaic cells with roofing products such as shingles,shakes or tiles. A plurality of photovoltaic roofing elements (i.e.,including photovoltaic media integrated with a roofing product) can beinstalled together on a roof, and electrically interconnected to form aphotovoltaic roofing system that provides both environmental protectionand photovoltaic power generation.

Roofing products equipped with photovoltaic media often requireelectrical connectors to be attached to the products to allowelectricity to be collected from photovoltaic cells and delivered to anelectrical system. Such connectors can be, for example, mated connectorsfor connecting adjacent photovoltaic roofing elements, cables forconnecting photovoltaic elements to the mated connectors, and/orjunction boxes for interconnections within a single photovoltaic roofingelement. The interface between such connectors can be susceptible toingress of moisture. Even when the mated connectors are covered byoverlying roofing elements, wind-driven moisture can work its way up theroof underneath the overlying roofing elements and into the connection.

Moreover, such devices must be robust to maintain the electricalconnection in use and over time. In some cases, bulky connectors withsafety locks may be required depending on the accessibility of theelectrical connection. If the electrical connector will be covered bythe roofing product in use, requirements can be less extreme, but arobust connection remains necessary. There exist low-profile connectors,but even these can be difficult to integrate with thin roofing productslike asphalt or bituminous roofing shingles. For the case where theroofing product is thin or of low thickness, a low profile or flatterstyle of connector may be used. When such a low profile connector isused, useful connectors are often still quite bulky with respect to athin roofing product such as, for example, an asphalt or bituminousroofing shingle equipped with photovoltaic media. Bulky connectorsunderlying the roofing product may telegraph their structure to the topsurface of the shingle resulting in a wavy or distorted appearance thatis undesirable. The local telegraphing of bumps over connectors can alsolead to stress points and wear points on or in the roofing material andhave deleterious effect on product performance. Other electricalelements, such as cables and junction boxes can also cause undesirableaesthetic appearance and stress/wear points. Moreover, electricalconnectors can often be susceptible to ingress of water blown up theroof by wind, even when they are disposed beneath a shingle or otherroofing element.

There remains a need for photovoltaic roofing products that address oneor more of these deficiencies.

SUMMARY OF THE INVENTION

One aspect of the invention is a photovoltaic roofing element including

-   -   a roofing substrate;    -   a photovoltaic element disposed on the roofing substrate;    -   an electrical connector operatively connected to the        photovoltaic element, the electrical connector having a top        side, a down-roof side and an electrical terminus; and    -   a shield disposed adjacent the electrical terminus of the        electrical connector on its down-roof side, its top side, or        both.

Another aspect of the invention is a photovoltaic roofing systemincluding an electrically-interconnected plurality of photovoltaicroofing elements, each including

-   -   a roofing substrate;    -   a photovoltaic element disposed on the roofing substrate;    -   an electrical connector operatively connected to the        photovoltaic element, the electrical connector having a top        side, a down-roof side and an electrical terminus; and    -   a shield disposed adjacent the electrical terminus of the        electrical connector on its down-roof side, its top side, or        both.

Another aspect of the invention is a method for installing aphotovoltaic roofing system, the method including disposing on a roofdeck and electrically interconnecting a plurality of photovoltaicroofing elements, each including

-   -   a roofing substrate;    -   a photovoltaic element disposed on the roofing substrate;    -   an electrical connector operatively connected to the        photovoltaic element, the electrical connector having a top        side, a down-roof side and an electrical terminus; and    -   a shield disposed adjacent the electrical terminus of the        electrical connector on its down-roof side, its top side, or        both.

The invention will be further described with reference to embodimentsdepicted the appended figures. It will be appreciated that elements inthe figures are illustrated for simplicity and clarity and have notnecessarily been drawn to scale. For example, the dimensions of some ofthe elements in the figures may be exaggerated relative to otherelements to help to improve understanding of embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not necessarily to scale, and sizes ofvarious elements can be distorted for clarity.

FIG. 1 is a partial top schematic view, and FIG. 2 is a partialschematic cross-sectional view of a photovoltaic roofing elementaccording to one embodiment of the invention;

FIG. 3 is a top schematic view of an electrical connector and a shieldaccording to another embodiment of the invention;

FIGS. 4 and 5 are a partial schematic cross-sectional views osphotovoltaic roofing elements according to other embodiments of theinvention;

FIG. 6 is a set of schematic cross-sectional views of flangeconfigurations according to certain embodiments of the invention;

FIG. 7 is a schematic exploded view of an encapsulated photovoltaicelement suitable for use in practicing various embodiments of theinvention;

FIG. 8 is a set of pictures of electrical connectors that can besuitable for use or adapted for use in practicing various embodiments ofthe invention;

FIG. 9 is a schematic top view, and FIG. 10 a schematic cross-sectionalview of a photovoltaic roofing element according to one embodiment ofthe invention;

FIG. 11 is a schematic cross-sectional view of a photovoltaic roofingelement according to another embodiment of the invention;

FIGS. 12 and 13 are schematic top views of photovoltaic roofing elementsaccording to certain embodiments of the invention;

FIG. 14 is a schematic top view, and FIG. 15 a schematic cross-sectionalview of a photovoltaic roofing element according to one embodiment ofthe invention;

FIG. 16 is a schematic cross-sectional view of a photovoltaic roofingelement according to another embodiment of the invention;

FIG. 17 is a schematic top view, and FIG. 18 a schematic cross-sectionalview of a photovoltaic roofing element according to another embodimentof the invention;

FIG. 19 is a partial schematic top view of a photovoltaic roofing systemaccording to one embodiment of the invention;

FIGS. 20 and 21 are partial schematic cross-sectional views ofphotovoltaic roofing systems according to certain embodiments of theinvention;

FIGS. 22 and 23 are partial schematic top views of photovoltaic systemsaccording to certain embodiments of the invention;

FIG. 24 is a schematic cross-sectional view and FIG. 25 is a schematictop view of a photovoltaic roofing element according to one embodimentof the invention;

FIG. 26 is a schematic cross-sectional view of a photovoltaic roofingsystem according to one embodiment of the invention;

FIG. 27 is a schematic cross-sectional view and FIG. 28 is a schematictop view of a photovoltaic element according to another embodiment ofthe invention;

FIG. 29 is a schematic cross-sectional view of a photovoltaic roofingsystem according to one embodiment of the invention;

FIG. 30 is a schematic top view and FIG. 31 is a schematiccross-sectional view of a photovoltaic element according to anotherembodiment of the invention;

FIG. 32 is a schematic cross-sectional view of a photovoltaic elementaccording to another embodiment of the invention;

FIG. 33 is a schematic cross-sectional view and FIG. 34 is a schematictop view of a photovoltaic roofing element according to anotherembodiment of the invention; and

FIGS. 35 and 36 are schematic cross-sectional views of photovoltaicroofing elements according to other embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the invention is a photovoltaic roofing element comprisinga roofing substrate; a photovoltaic element disposed on the roofingsubstrate; an electrical connector operatively connected to thephotovoltaic element, the electrical connector having a top side, adown-roof side and an electrical terminus; and a shield disposedadjacent the electrical terminus of the electrical connector on itsdown-roof side, its top side, or both. For example, in certainembodiments, the shield is disposed adjacent the electrical terminus ofthe electrical connector at least on its down-roof side. In otherembodiments, the shield is disposed adjacent the electrical terminus ofthe electrical connector at least on its top side. As described in moredetail below, the shield can be provided as part of the electricalconnector, part of the roofing element, or as a separate piece assembledtherewith.

One embodiment of the invention is shown in partial top schematic viewin FIG. 1, and in partial schematic cross-sectional view in FIG. 2. Aphotovoltaic roofing element 100 comprises a roofing substrate 110; aphotovoltaic element 140 disposed on the roofing substrate; anelectrical connector 150 operatively connected to the photovoltaicelement (e.g., through cable 152), the electrical connector having adown-roof side 154, a top side 155 and an electrical terminus 156. Thephotovoltaic roofing element also includes a shield 170 disposedadjacent the electrical terminus, so that it spans the interface 174between the electrical connector 150 and a mating electrical connector180 (shown in dotted outline) from an adjacent photovoltaic roofingelement. Such a shield can help protect the electrical connection fromwind-blown rain.

In certain embodiments, the shield is in substantial contact with theroofing substrate, as shown in FIG. 2. In such embodiments, the shieldcan block wind-blown moisture from running up the surface of thephotovoltaic roofing element and into electrical terminus of theelectrical connector (e.g., at the point of interconnection betweeninterconnected connectors). In certain embodiments, the shield isattached to the roofing substrate (e.g., by nailing the horizontalportion of the shield through the roofing substrate and into the roofdeck, or otherwise attaching the shield to the roofing substrate). Inother embodiments, the shield is merely disposed on the roofingsubstrate. The shield, can, for example, be held against the roofingsubstrate by pressure from overlying photovoltaic roofing elements. Theshield can, for example, be sealed to roofing substrate with a sealant,for example, an adhesive or a layer of polymer against which the shieldis disposed, so as to prevent water from penetrating beneath the shield.In other embodiments, the shield is formed as part of the roofingsubstrate (e.g., in a compression molded substrate as described in U.S.Patent Application Publication no. 2009/0000222, which is herebyincorporated herein by reference in its entirety).

In the embodiments of FIGS. 1 and 2, the shield is an element disposedon the roofing substrate and extending away from the substrate,positioned in front of (i.e., down-roof from) the electrical terminus ofthe electrical connector (i.e., from where the interface betweenconnectors would be when the electrical connector is interconnected withanother electrical connector, e.g., from another photovoltaic roofingelement or from a wiring system.

In other embodiments, the shield can be, for example, integrally formedwith the electrical connector, or otherwise physically connected to theconnector. For example, the connector 350 shown in schematic top view inFIG. 3 has a shield 370 on its down roof-side 354 extending from its endbearing electrical terminus 356. When connected with a mating connector380 (shown in dotted outline), the shield is disposed in front of theinterface 374 between the two, helping to protect it from moisturemigrating up the roof (e.g., due to wind).

Another embodiment is shown in partial schematic cross-sectional view inFIG. 4. In this embodiment, the electrical connector 450 is protected byshield 470 (e.g., disposed adjacent or attached thereto as describedabove). Shield 470 covers the electrical connector on its down-roof side458 and its top side 461, protecting the interface between theelectrical connector 450 and an adjacent electrical connector (notshown), e.g., from wiring system or adjacent photovoltaic roofingelement, that mates therewith. As described above, the shield can be,for example, attached to the electrical connector (e.g., through a snapfit or adhered using adhesive), or integrally formed therewith (e.g.,from a single molded plastic article). In other embodiments, the shieldcan be attached to the roof, and simply rests over the connector.Moreover, while the shield 470 is shown as being in contact with the topsurface 461 of the electrical connector 450 in FIG. 4, in otherembodiments there can be space in between.

In certain embodiments, for example as shown in FIGS. 1 and 2, theterminus of the electrical connector is oriented laterally, as opposedto up- or down the roof and the shield is disposed adjacent theelectrical terminus on its down-roof side. The shield can also protectother sides of the interface between the electrical connectors, forexample, the top side (i.e., relative to the plane of the roof), forexample, as shown in FIG. 4.

In certain embodiments, the shield is disposed adjacent the electricalconnector on its top side. Another embodiment is shown in sidecross-sectional schematic view in FIG. 5. In this embodiment, theelectrical connector 550 has its electrical terminus 556 on the up-roofside of the electrical connector. Shield 570 covers the electricalconnector on its top side 561, protecting the interface 574 between theelectrical connector 550 and the electrical connector 580 (shown indotted outline), e.g., from a wiring system or adjacent photovoltaicroofing element, that mates therewith. As described above, the shieldcan be, for example, attached to the electrical connector e.g., througha snap fit, or integrally formed therewith (e.g., from a single moldedplastic article).

In certain embodiments, for example as shown in FIG. 5, the terminus ofthe electrical connector is oriented up the roof and the shield isdisposed adjacent the electrical terminus on its top side. The shieldcan also protect other sides of the interface between the electricalconnectors, for example, the down-roof side.

In certain embodiments, the shield can have a vertical or down-roofpointing flange, for example as shown by reference number 572 in FIG. 5.Such a flange can help to keep water from working its way over the topof the shield and down into the electrical interface. A variety ofpossible configurations for the flange are shown in schematiccross-sectional view in FIG. 6. The flange can, for example, point in avertical direction (i.e., substantially perpendicular to the plane ofthe roofing element on which it is disposed), as shown in shield 672, orcan point in the down-roof direction (i.e., angle away from theperpendicular in the down-roof direction), as shown in shields 674 and676. The flange can be, for example, a folded-over section of thematerial used to make the shield.

In certain embodiments, the shield has a lateral dimension (e.g., in adirection parallel to the roof and perpendicular to the slope of theroof, as shown by arrow “L” in FIG. 3) of at least about 1 cm (e.g., inthe range of about 1 cm to about 5 cm). In certain embodiments, theshield has a vertical dimension (e.g., in a direction perpendicular tothe plane of the roof) of at least about 0.5 cm, or even about 1 cm(e.g., in the range of about 1 cm to about 3 cm), as shown by arrow “H”in FIG. 2. In certain embodiments, the vertical dimension of the shieldis at least about 50% of the height of the electrical connector. Ofcourse, as the person of skill will recognize, the vertical dimension ofthe shield need only be sufficient to provide the desiredmoisture-blocking properties.

Shields suitable for use in the present invention can be formed from avariety of materials, for example, plastic or metal. A variety oftechniques can be used by the person of skill in the art to fabricateand install shields, as would be apparent to the person of skill in theart. Moreover, the shields can be installed onto the roofing element atany convenient time, for example, before it is installed on the roof,after it is installed on the roof, or even after installation andconnection of the photovoltaic elements.

Photovoltaic elements suitable for use in the various aspects of thepresent invention include one or more interconnected photovoltaic cellsprovided together, for example, in a single package. The photovoltaiccells of the photovoltaic elements can be based on any desirablephotovoltaic material system, such as monocrystalline silicon;polycrystalline silicon; amorphous silicon; III-V materials such asindium gallium nitride; Il-VI materials such as cadmium telluride; andmore complex chalcogenides (group VI) and pnicogenides (group V) such ascopper indium diselenide and copper indium gallium selenide. Forexample, one type of suitable photovoltaic cell includes an n-typesilicon layer (doped with an electron donor such as phosphorus) orientedtoward incident solar radiation on top of a p-type silicon layer (dopedwith an electron acceptor, such as boron), sandwiched between a pair ofelectrically-conductive electrode layers. Another type of suitablephotovoltaic cell is an indium phosphide-based thermo-photovoltaic cell,which has high energy conversion efficiency in the near-infrared regionof the solar spectrum. Thin film photovoltaic materials and flexiblephotovoltaic materials can be used in the construction of photovoltaicelements for use in the present invention. In one embodiment of theinvention, the photovoltaic element includes a monocrystalline siliconphotovoltaic cell or a polycrystalline silicon photovoltaic cell. Thephotovoltaic elements for use in the present invention can be flexible,or alternatively can be rigid.

The photovoltaic elements can be encapsulated photovoltaic elements, inwhich photovoltaic cells are encapsulated between various layers ofmaterial (e.g., as a laminate). For example, a photovoltaic laminate caninclude a top laminate layer at its top surface, and a bottom laminatelayer at its bottom surface. The top laminate layer material can, forexample, provide environmental protection to the underlying photovoltaiccells, and any other underlying layers. Examples of suitable materialsfor the top layer material include fluoropolymers, for example ETFE(“TEFZEL”, or NORTON ETFE), PFE, FEP, PVF (“TEDLAR”), PCTFE or PVDF. Thetop laminate layer material can alternatively be, for example, a glasssheet, or a non-fluorinated polymeric material (e.g., polypropylene oracrylic). The bottom laminate layer material can be, for example, afluoropolymer, for example ETFE (“TEFZEL”, or NORTON ETFE), PFE, FEP,PVDF or PVF (“TEDLAR”). The bottom laminate layer material canalternatively be, for example, a polymeric material (e.g., polyolefinsuch as polypropylene, polyester such as PET); or a metallic material(e.g., steel or aluminum sheet).

As the person of skill in the art will appreciate, a photovoltaiclaminate can include other layers interspersed between the top laminatelayer and the bottom laminate layer. For example, a photovoltaiclaminate can include structural elements (e.g., a reinforcing layer ofglass, metal, glass or polymer fibers, a rigid film, or a flexiblefilm); adhesive layers (e.g., EVA to adhere other layers together);mounting structures (e.g., clips, holes, or tabs); one or moreelectrical components (e.g., electrodes, electrical connectors;optionally connectorized electrical wires or cables) for electricallyinterconnecting the photovoltaic cell(s) of the encapsulatedphotovoltaic element with an electrical system. As described in moredetail below, the return electrical path, any series interconnectionsbetween photovoltaic elements, and any bypass diodes can be includedwithin the laminate. An example of a photovoltaic laminate suitable foruse in the present invention is shown in schematic exploded view FIG. 7.Encapsulated photovoltaic element 750 includes a top protective layer752 (e.g., glass or a fluoropolymer film such as ETFE, PVDF, PVF, FEP,PFA or PCTFE); encapsulant layers 754 (e.g., EVA, functionalized EVA,crosslinked EVA, silicone, thermoplastic polyurethane, maleicacid-modified polyolefin, ionomer, or ethylene/(meth)acrylic acidcopolymer); a layer of electrically-interconnected photovoltaic cells756 (which can include the return electrical path and bypass diode asdescribed above); and a backing layer 758 (e.g., PVDF, PVF, PET).

The photovoltaic element can include at least one antireflectioncoating, for example as the top layer material in an encapsulatedphotovoltaic element, or disposed between the top layer material and thephotovoltaic cells. The photovoltaic element can also be made colored,textured, or patterned, for example by using colored, textured orpatterned layers in the construction of the photovoltaic element.Methods for adjusting the appearance of photovoltaic elements aredescribed, for example, in U.S. Provisional Patent Applications Ser. No.61/019,740, and U.S. patent application Ser. Nos. 11/456,200,11/742,909, 12/145,166, 12/266,481 and 12/267,458 each of which ishereby incorporated herein by reference.

Suitable photovoltaic elements can be obtained, for example, from ChinaElectric Equipment Group of Nanjing, China, as well as from severaldomestic suppliers such as Uni-Solar Ovonic, Sharp, Shell Solar, BPSolar, USFC, FirstSolar, Ascent Solar, General Electric, Schott Solar.Evergreen Solar and Global Solar. Moreover, the person of skill in theart can fabricate photovoltaic laminates using techniques such aslamination or autoclave processes. Photovoltaic laminates can be made,for example, using methods disclosed in U.S. Pat. No. 5,273,608, whichis hereby incorporated herein by reference. Flexible photovoltaicelements are commercially available from Uni-Solar as L-cells having adimension of approximately 9.5″×14″, S-cells having dimensions ofapproximately 4.75″×14″, and T-cells having dimensions of approximately4.75″×7″. Photovoltaic laminates of custom sizes can also be made.

The photovoltaic element also has an operating wavelength range. Solarradiation includes light of wavelengths spanning the near UV, thevisible, and the near infrared spectra. As used herein, the term “solarradiation,” when used without further elaboration means radiation in thewavelength range of 300 nm to 2500 nm, inclusive. Different photovoltaicelements have different power generation efficiencies with respect todifferent parts of the solar spectrum. Amorphous doped silicon is mostefficient at visible wavelengths, and polycrystalline doped silicon andmonocrystalline doped silicon are most efficient at near-infraredwavelengths. As used herein, the operating wavelength range of aphotovoltaic element is the wavelength range over which the relativespectral response is at least 10% of the maximal spectral response.According to certain embodiments of the invention, the operatingwavelength range of the photovoltaic element falls within the range ofabout 300 nm to about 2000 nm. In certain embodiments of the invention,the operating wavelength range of the photovoltaic element falls withinthe range of about 300 nm to about 1200 nm.

The person of skill in the art will select bypass diode characteristicsdepending on a number of factors. The characteristics of the diode willdepend, for example, on the type and size of photovoltaic element used,the intensity and variability of sunlight expected at the installationlocation, and the resistance at which a shaded photovoltaic elementcauses unacceptable system inefficiency. For example, the bypass diodecan be configured to bypass a photovoltaic element when its output dropsbelow about 30% of its maximum (i.e., in full sunlight at noon on thesolstice) output (i.e., a about 30% or greater degradation inphotovoltaically-generated current), below about 50% of its maximumoutput, below about 70% of its maximum output, below about 90% of itsmaximum output, or even below about 95% of its maximum output. Forexample, in one embodiment, in a 20 cell series-connected array of 1volt/5 amp producing photovoltaic elements, the bypass diodes can beselected to bypass the photovoltaic elements when the output currentdrops below 4.75 amps (i.e., below 95% of the maximum output). Ofcourse, as the person of skill will appreciate, each system design willhave its own set of parameters; with higher amperage systems, relativelymore degradation of current can be tolerated. In certain embodiments,the bypass diode can be an 8 amp bypass diode, available from NorthernArizona Wind & Sun, Flagstaff, Ariz.

In other embodiments, the bypass diode can be configured to bypass aphotovoltaic element when its resistivity increases by at least about400% of its resistivity at maximum output, at least about 300% of itsresistivity at maximum output, at least about 100% of its resistivity atmaximum output, at least about 50% of its resistivity at maximum output,at least about 25% of its resistivity at its maximum output, or even atleast about 5% of its resistivity at maximum output.

The present invention can be practiced using any of a number of types ofroofing substrates. In certain embodiments, the roofing substrate is aflexible roofing substrate. For example, the roofing substrate can be anasphalt shingle, a bituminous shingle or a plastic shingle. For example,the roofing substrate can be a multilayer asphalt shingle. Themanufacture of photovoltaic roofing elements using a variety of roofingsubstrates are described, for example, in U.S. patent application Ser.Nos. 12/146,986, 12/266,409, 12/268,313, 12/351,653, and 12/339,943, andU.S. Patent Application Publication no. 2007/0266562, each of which ishereby incorporated herein by reference in its entirety.

A variety of electrical connectors can be used in practicing the variousembodiments of the invention. An electrical connector can take the formof, for example, a mating electrical connector (i.e., adapted to matewith another mating electrical connector to make an electricalconnection therebetween). Mating connectors can mate with one another,for example, in a male/female fashion. An electrical connector can alsotake the form of a cable that interconnects a mating connector with thephotovoltaic element. An electrical connector can also take a form of ajunction box that interconnects various electrical wires and cablesassociated with the photovoltaic elements, mating connectors or otherelectrical components such as bypass diodes. Any or all of these typesof electrical connectors may be protected by a shield as describedherein.

Examples of electrical connectors that can be suitable for use oradapted for use in practicing various embodiments of the invention areshown in FIG. 8. The mating connectors and junction boxes depicted areavailable from Kyocera, Tyco Electronics, Berwyn, Pa. (trade nameSolarlok) and Multi-Contact USA of Santa Rosa, Calif. (trade nameSolarline). U.S. Pat. Nos. 7,445,508 and 7,387,537. U.S. patentapplication Ser. Nos. 11/743,073, 12/266,498, 12/268,313, 12/359,978 andU.S. Provisional Patent Application Ser. No. 61/121,130, each of whichis hereby incorporated herein by reference in its entirety, discloseelectrical connectors for use with photovoltaic roofing products. All ofthese electrical connectors are relatively flat and low in profilecompared to some other connectors, but they can still be thicker thantypical flexible roofing materials such as, for example, asphaltshingles, and would generally have a larger thickness dimension than aphotovoltaic laminate structure. Accordingly, their use with typicalflexible roofing materials would result in undesirable appearance andstress/wear points, as described above. Accordingly, such electricalconnectors can be useful in practicing various aspects of the presentinvention. Electrical connectors desirably meet UNDERWRITERSLABORATORIES and NATIONAL ELECTRICAL CODE standards.

In certain embodiments, the roofing substrate has formed therein arecess shaped to at least partially receive the electrical connector.The recess can be formed, for example, in a top or a bottom surface ofthe photovoltaic roofing element, or along a side of the photovoltaicroofing element (e.g., as a “notch” or a “cutout”).

The electrical connector and the shield can in certain embodiments bedisposed in the recess. For example, the electrical connector and theshield can in certain embodiments be affixedly disposed in the recess.In certain embodiments, the electrical connector can be generallymovable with respect to the recess, and disposed in the recess when thephotovoltaic roofing element is installed. For example, the electricalconnector can be a cable and/or a mating electrical connector that ismovable in order to be connected to an adjacent photovoltaic roofingelement or to an electrical bus or wiring system for collection ofelectrical power, then disposed in the recess once connected. In certainembodiments of the invention, the electrical connector and the shieldhave a thickness dimension that is greater than the thickness of thephotovoltaic element, and the roofing substrate has a recess formedtherein of appropriate size and shape to receive the volume of theelectrical connector and the shield when the photovoltaic roofingelement is installed on a roof. In some cases, the recess is formed inthe roofing substrate of a given photovoltaic roofing element, anddisposed so as to contain at least part of the volume of the electricalconnector and the shield of the same photovoltaic roofing element. Inother embodiments, the recess is disposed so as to contain at least partof the volume of an electrical connector and a shield of a differentphotovoltaic roofing element, for example an underlying photovoltaicroofing element, or an overlying photovoltaic roofing element.

In certain embodiments of the invention, the recess can be disposed toretain an electrical connector and a shield inlayed in the material sothat a bump or surface irregularity that may otherwise telegraph throughto a shingle of an overlying course is avoided. In certain embodiments,the recess is formed as a cutout or notch in some, but not all, layersof a multilayer laminate roofing substrate (e.g., an asphalt shingle).In some embodiments, a continuous notch running the length of theshingle is provided that can contain one or more connectors (e.g.,cables and mating connectors) along with their associated shields. Insome cases, additional shingle shim material may be employed in thevicinity of the electrical connector and the shield to offset athickness differential in the roofing product near them.

FIG. 9 is a schematic top view and FIG. 10 is a schematic side view of aphotovoltaic roofing element according to one embodiment of theinvention. Photovoltaic roofing element 900 includes a roofing substrate910 (here, an asphalt shingle) having a exposure zone 912 (i.e., thepart of the shingle that will be exposed when installed on a roof) and aheadlap zone 914 (the part that will be covered by an overlying courseof shingles). A photovoltaic element 950 is disposed on the flexibleroofing substrate in the exposure zone. The photovoltaic element furtherincludes two electrical connectors (here, mating electrical connectors)920 and 922, which are operatively coupled to the photovoltaic element950, in this embodiment through wires 924. The mating electricalconnectors in this embodiment mate in a male/female fashion. Disposed inthe recess is a shield 970, attached to the down-roof side of the femaleconnector 920, as described above. The roofing substrate has recesses930 and 932 formed therein, which are adapted to at least partiallyreceive the mating electrical connectors 920 and 922.

In the embodiment of FIGS. 9 and 10 the electrical connectors aredisposed entirely within the recesses. In other embodiments, theelectrical connectors can be only partially disposed within therecesses; that is, some portion of an electrical connector can in somecircumstances protrude from the recess. The electrical connectors can beaffixed into the recesses, or alternatively can be merely held withinthem.

In cases where no recess is provided for the wires connecting thephotovoltaic element to the mating electrical connector, they aredesirably relatively flat in cross-sectional shape, so as not to cause asignificant bump in an overlying roofing element. In certain otherembodiments, the wires are disposed within the flexible roofingsubstrate itself.

The recess can be formed in a variety of surfaces of the roofingsubstrate. For example, as shown in FIGS. 9 and 10, the recess can beformed in a top surface of the roofing substrate. As shown in FIG. 10,in certain embodiments, the recess does not go through the thickness ofthe entire asphalt shingle.

Another embodiment is shown in cross-sectional view in FIG. 11. In thisphotovoltaic roofing element 1100, the top view is similar to that shownin FIG. 9, but the recess is formed in the side of the roofing substrate1110, and the recess 1130 goes all the way through the roofingsubstrate. Also, in this embodiment, the shield 1170 is integrallyformed with connector 1120, for example, by injection molding of asingle plastic piece. This configuration can be advantaged in that itwould prevent pooling of any water that is blown-back up underneath theoverlying roofing elements.

A recess can be formed through less than all layers of a multilayerasphalt shingle (or other roofing substrate). For example, the recesscan be formed as a hole or cutout in at least one, but not all thelayers of a multilayer asphalt shingle.

Another embodiment is shown in top schematic view in FIG. 12. Inphotovoltaic roofing element 1200, the flexible roofing substrate 1210has a recess which is adapted to at least partially receive not only themating electrical connector 1220, which has shield 1270 on its topsurface as described above, and electrical connector 1222, but also thewires 1224 that operatively connect them to the photovoltaic element1250. In this embodiment, the wires can be relatively thick, but stillnot cause distortion of overlying layers of roofing materials. In otherembodiments, the recess can be shaped to at least partially receiveother electrical connectors, such as bypass diodes and junction boxes.

Another embodiment is shown in top schematic view in FIG. 13. In thisembodiment, the recess 1330 is formed in a bottom surface of theflexible roofing substrate. The mating electrical connectors 1320, 1322,the shield 1370 disposed on the roofing substrate down-roof ofelectrical connector 1320, and the wires 1324 are disposed on the topsurface of the flexible roofing substrate 1310. In this embodiment, therecess is of a shape to at least partially receive the electricalconnectors. However, when installed, the mating electrical connectors ofthis photovoltaic roofing element 1300 will not be disposed within therecess 1330. Rather, as will be described in more detail with referenceto FIG. 21, in use the recess 1330 of this photovoltaic roofing elementcan at least partially receive the electrical connectors of a similar,underlying photovoltaic roofing element, and the electrical connectors1320, 1322 of this photovoltaic roofing element 1330 can be at leastpartially received by the recess of a similar, overlying photovoltaicroofing element.

In other embodiments, as shown in top view in FIG. 14, andcross-sectional view in FIG. 15, the electrical connector is partiallyreceived within the recess, yet protrudes partially from the top face ofthe photovoltaic roofing element. In photovoltaic element 1400, thephotovoltaic elements 1450 and their associated series interconnectionwiring 1424, bypass diode 1426 and return electrical path wiring 1428,along with mating electrical connectors 1420 and 1422 are containedwithin a laminate or encapsulated structure 1480, from which the matingelectrical connectors protrude. Shield 1470, which has flange 1472formed thereon as described above, is disposed on the top surface ofconnector 1420. The return electrical path wiring can allow for themating electrical connectors to not only interconnect the photovoltaicelements of adjacent photovoltaic roofing elements in series, but alsoallow provide the return path for built-up power to the largerelectrical system. The return path wiring can be as described in U.S.Patent Application Publication no. 2009/0242015, which is herebyincorporated herein by reference in its entirety. In the embodiment ofFIGS. 14 and 15, the mating electrical connectors protrude from both thebottom and top faces of the laminate structure. In other embodiments,the mating electrical connectors protrude only from the top surface, oronly from the bottom surface of the laminate or encapsulated structure.In the embodiment of FIGS. 14 and 15, the laminate structure 1480 isdisposed on a roofing substrate 1410. The roofing substrate 1410 has arecess 1430 formed therein to receive the mating electrical connector1420; as well as a second recess formed therein (not shown in thecross-sectional view of FIG. 15) to receive the mating electricalconnector 1422. In certain embodiments, for example when the electricalconnectors protrude significantly from the top face of the laminate orencapsulated structure, the flexible roofing substrate 1410 can have arecess formed in its bottom surface, as described above with referenceto FIG. 13 and below with reference to FIG. 21.

In certain embodiments, the flexible roofing substrate itself is madefrom a plurality of layers of material. In such embodiments, the variouslayers can be cut or notched differently to form the recess. Forexample, in the embodiment of FIG. 16, the roofing substrate 1610includes two layers of material (e.g., asphalt-impregnated fiberglassweb, as used in conventional roofing shingles). In the first layer 1612,a notch 1634 (shown as a discontinuity in this cross-sectional view) iscut to receive the electrical connector 1620 (which has shield 1670attached thereto). The second layer 1614 underlies the first layer andthe electrical connector. The overall effect of the notch 1634 and theunderlying layer 1614 is that of a recess formed in the top surface ofthe flexible roofing substrate, as described above.

In certain embodiments of the invention, the wiring that operativelyconnects the mating electrical connectors to the photovoltaic elementcan have sufficient slack to allow the connectors to be lifted away fromthe flexible roofing substrate for easy interconnection with the matingelectrical connector of another photovoltaic roofing element, or into alarger electrical system. In some such embodiments, the slack wire canbe received by a recess in a roofing substrate (i.e., either in theroofing substrate of its own photovoltaic roofing element, or theroofing substrate of an overlying photovoltaic roofing element, asdescribed above with reference to FIG. 13 and below with reference toFIG. 21. An example of this is shown in FIG. 12, in which the slack inwiring 1224 is received by recess 1230.

FIG. 17 is a top schematic view, and FIG. 18 is a cross-sectionalschematic view of a photovoltaic roofing element 1700 according toanother embodiment of the invention. In this embodiment, the laminate orencapsulate structure 1780 has a reduced volume of encapsulant orlaminating materials in the headlap zone of the structure (i.e., thereis no encapsulant or laminating material in most of the headlap zone1718 of the photovoltaic roofing element 1700). Such an arrangement canmake more efficient use of costly encapsulant or laminating materials byencapsulating or laminating primarily the parts of the structure thatinclude electrical wiring or photovoltaic materials, and generallyavoiding the use of encapsulant or laminate materials in portions of thestructure that will not be exposed to the weather. In other embodiments,wires or cables can connect the mating electrical connectors to alaminated or encapsulated photovoltaic element.

In the photovoltaic roofing element of FIGS. 17 and 18, the laminate orencapsulate structure 1780 includes photovoltaic elements 1750, bypassdiode 1726, return path wiring 1728 and wiring 1724, as well as matingelectrical connectors 1720, 1722 (which includes shield 1770 asdescribed above). The mating electrical connectors protrude both andabove and below the laminate or encapsulate structure. The flexibleroofing substrate 1710 includes a first layer 1712 which has a notch1734 cut therein to receive the mating electrical connector 1720, and asecond layer 1714 which underlies the first layer. In certainembodiments, the first layer merely has a recess formed therein, insteadof a notch formed through its entire thickness. The second layer doesnot have notches in the vicinity of the mating electrical connectors,thus providing closure and a water and weather proofing of thephotovoltaic roofing element. The photovoltaic roofing element 1700 alsoincludes a top layer of flexible roofing material 1790 (shown in dottedoutline in FIG. 17) in the headlap zone, which has a notch formedtherein to accommodate the mating electrical connectors. In thisembodiment, the mating electrical connectors protrude only slightlyabove the top layer of flexible roofing material, and when installed haslittle effect on the aesthetics of an overlying photovoltaic roofingelement. In other embodiments, the second layer of the flexible roofingsubstrate has a hole cut therein, to form a recess formed in the bottomsurface of the flexible roofing substrate, as described above withreference to FIG. 13 and below with reference to FIG. 21.

Another aspect of the invention is shown in partial schematic top viewin FIG. 19. Photovoltaic roofing system 1990 includes a first and asecond photovoltaic roofing element 1900 and 1902 electricallyinterconnected with one another, each of which comprises a roofingsubstrate, a photovoltaic element disposed on the roofing substrate, anelectrical connector operatively coupled to the photovoltaic element,and a shield, as described above. Photovoltaic roofing system 1990further comprises a third photovoltaic roofing element 1905, shown indotted outline, which comprises a roofing substrate, a photovoltaicelement disposed on the roofing substrate, and an electrical connectoroperatively coupled to the photovoltaic element, as described above. Thethird photovoltaic roofing element 1905 is disposed so as to cover theinterconnected electrical connectors of the first and secondphotovoltaic roofing element (shown generally by reference number 1904).In certain embodiments, the electrical connectors of the first andsecond photovoltaic roofing elements are at least partially disposedwithin a recess formed in the roofing substrate of the first and/orsecond photovoltaic roofing elements (e.g., in a top or along a sidethereof); within a recess formed in the roofing substrate of the thirdphotovoltaic roofing element (e.g., in a bottom surface thereof); orwithin a recess formed in the roofing substrate of the first and/orsecond photovoltaic roofing elements and within a recess formed in theroofing substrate of the second photovoltaic roofing element. The thirdphotovoltaic roofing element can be electrically interconnected to thefirst and second photovoltaic roofing elements, for example, by otherphotovoltaic roofing elements (not shown) and/or a wiring system (notshown). The photovoltaic roofing system can, for example, be disposed ona roof deck.

For example, in certain embodiments, as shown in side cross-sectionalview in FIG. 20, the roofing substrate of the first photovoltaic roofingelement 2000 has a recess 2030 formed in its top surface or along aside, in which the electrical connector of the first photovoltaicroofing element is at least partially disposed. Such a photovoltaicroofing element is described, for example, with reference to FIGS. 9 and10, above. In FIG. 20, the electrical connector 2020 and shield 2070 offirst photovoltaic roofing element 2000 is covered by secondphotovoltaic roofing element 2005 (shown in dotted outline). As theperson of skill in the art will understand, the recesses (e.g., cutoutsor notches) can advantageously be disposed so that, when installed, theyare aligned in a way to minimize the formation of water pathways throughthe roofing substrates.

The shield can be disposed so that it spans two adjacent photovoltaicroofing elements, for example to protect the interface of an electricalconnection made across the photovoltaic roofing elements. Accordingly,another embodiment of the invention is a photovoltaic roofing arraycomprising a first photovoltaic roofing element and a secondphotovoltaic roofing element disposed adjacent one another, the firstphotovoltaic roofing element and the second photovoltaic roofing elementeach comprising a roofing substrate; a photovoltaic element disposed onthe roofing substrate; and an electrical connector operatively connectedto the photovoltaic element, the electrical connector having a down-roofside and an electrical terminus, the electrical connectors of the firstphotovoltaic roofing element and the second photovoltaic roofing elementbeing interconnected at an interface; and a shield disposed adjacent theinterface between the electrical connectors of the first and secondphotovoltaic roofing elements on its down-roof side, its top side, orboth. In one embodiment, the shield is in substantial contact with theroofing substrate. For example, the shield can be a separate elementattached to the roofing substrate and extending away from the substrate,positioned in front of the terminus of the electrical connector. Incertain embodiments, the shield is disposed across the firstphotovoltaic roofing element and the second photovoltaic roofingelement. In other embodiments, it is disposed on one or the other ofthem. The shield can be integrally formed with the roofing substrate;integrally formed with the connector, or attached separately. The personof skill in the art can adapt the shield configurations described abovefor such embodiments.

Another aspect of the invention is a photovoltaic roofing systemincluding a first photovoltaic roofing element, the first photovoltaicroofing element comprising a roofing substrate, a photovoltaic elementdisposed on the roofing substrate, an electrical connector operativelycoupled to the photovoltaic element and a shield disposed adjacent theelectrical terminus of the electrical connector on its down-roof side,its top side, or both; and a second photovoltaic roofing elementdisposed adjacent the first photovoltaic roofing element, the secondphotovoltaic roofing element comprising: a roofing substrate having arecess formed therein, the electrical connector and the shield of thefirst photovoltaic roofing element being at least partially disposed inthe recess, a photovoltaic element disposed on the roofing substrate,and an electrical connector operatively coupled to the photovoltaicelement. For example, as shown in side cross-sectional view in FIG. 21,the roofing substrate of the second photovoltaic roofing element has arecess formed in its bottom surface, in which the electrical connectorof the first photovoltaic roofing element is at least partiallydisposed. Such a photovoltaic roofing element is described, for example,with reference to FIG. 13, above. In FIG. 21, the electrical connector2120 and shield 2170 of the first photovoltaic roofing element 2100 isdisposed in a recess 2130 formed in the bottom side of the roofingsubstrate of the second photovoltaic roofing element 2105 (shown indotted outline). While not shown in this cross-sectional view (due tothe lateral offset between the photovoltaic roofing elements as shown inFIG. 19), the second photovoltaic roofing element can have a electricalconnector, and the first photovoltaic roofing element can have a recessformed in the bottom surface of its roofing substrate. For example, thefirst and second photovoltaic roofing elements can be the same. As theperson of skill in the art will appreciate, the position of the recesswill depend on the positions of the electrical connectors as well as theintended configuration (i.e., lateral offset between courses, degree ofoverlap between courses) of the photovoltaic roofing elements in alarger photovoltaic roofing system. For example, if a photovoltaicroofing element has its electrical connectors at a higher position(i.e., closer to the roof ridge end of the photovoltaic roofingelement), a recess on the bottom surface would be at a differentlocation than for embodiments having electrical connectors at a lowerposition. For photovoltaic roofing elements to be applied with aconsistent lateral offset during installation, a recess can beappropriately located so as to be able to receive the electricalconnectors and shield of an underlying course. For photovoltaic roofingelements that are to be applied with an alternating offset, such as in aracked-type installation, it may be that they include two recesses, onetoward a left end and one toward a right end so that the samephotovoltaic roofing elements may be used as courses are built up on theroof with alternating left and right offsets in the installationpattern.

FIG. 22 shows a photovoltaic roofing system comprising an array ofphotovoltaic roofing elements as described herein. The photovoltaicroofing elements are disposed in a laterally-offset fashion assequential courses are applied on a roof deck (roof deck not shown). Asthe person of skill in the art will understand, the number of coursesand the number of photovoltaic roofing elements per course will dependon the size of the roof area to be covered, and may include more orfewer courses than three, and more or fewer photovoltaic roofingelements per course than three. In FIG. 22, the upper two courses areshown in dotted outline, so as to show the locations of the structuraldetails of the underlying courses, including the locations of theelectrical connectors and interconnections between photovoltaic roofingelements. As described in detail above, the electrical connectors can bedisposed within recesses formed in the photovoltaic roofing elements ofwhich they are a part, within recess formed in overlying photovoltaicroofing elements, or (advantageously for relatively thick electricalconnectors) both.

FIG. 23 shows a photovoltaic roofing system similar to that of FIG. 22,in which the photovoltaic roofing elements are disposed in a rackedconfiguration, in which the laterally offset disposition as sequentialcourses are applied on a roof deck (roof deck not shown) alternates fromleft to right relative to the underlying course moving up the roof.

One aspect of the invention is a photovoltaic roofing element includinga flexible roofing substrate, the roofing substrate including a base ofroofing material having a top surface, the top surface having a headlapzone and an exposure zone, and one or more layers of shim materialdisposed on the top surface of the base in the headlap zone; aphotovoltaic element disposed on the top surface of the base; anelectrical connector operatively connected to the photovoltaic elementand disposed on the top surface of the base, and a shield disposedadjacent the electrical terminus of the electrical connector on itsdown-roof side, its top side, or both, wherein the one or more layers ofshim material have a total thickness at least about as great as thethicknesses of the electrical connector and the shield. That is, thecombined thicknesses of the one or more layers of shim material is atleast about as great as the thickness of the combination of theelectrical connector and the shield.

For example, the total thickness of the one or more layers of shimmaterial can be about equal to (e.g., within 20% of, or even within 10%of) the thickness of the combination of the electrical connector and theshield. As used herein, the headlap zone is the area that is covered byoverlying courses of roofing elements when installed; and the exposurezone is the area that is not covered by overlying courses of roofingelements when installed.

In one embodiment, the one or more layers of shim material have astair-step configuration, for example with the region of greatestthickness disposed adjacent the electrical connector. In such anembodiment, the stair-step can provide a gradual slope to an overlyingroofing element.

In one embodiment, the one or more layers of shim material have a notchor recess formed therein, in which the connector and the shield arepositioned.

Another aspect of the invention is a photovoltaic roofing elementincluding a roofing substrate, the roofing substrate including a base ofroofing material having a top surface and a bottom surface, the topsurface having a headlap zone and an exposure zone; and one or morelayers of shim material disposed on the bottom surface of the roofingsubstrate; a photovoltaic element disposed on the top surface of thebase; an electrical connector operatively connected to the photovoltaicelement and disposed on the top surface of the base; and a shielddisposed adjacent the electrical terminus of the electrical connector onits down-roof side, its top side, or both, wherein the one or morelayers of roofing material have a total thickness at least about asgreat as the thicknesses of the electrical connector and the shield.

For example, the total thickness of the one or more layers of roofingmaterial can be about equal to (e.g., within 20% of, or even within 10%of) the thickness of the combination of the electrical connector and theshield.

In certain embodiments, the photovoltaic roofing element includes aplurality of electrical connectors, for example, mating electricalconnectors, junction boxes, bypass diodes, wiring and/or cabling. Any orall of the electrical connectors can be protected by the shim layers asdescribed herein.

In one embodiment, the one or more layers of shim material arepositioned so that, when installed, the electrical connector of anunderlying photovoltaic roofing element is disposed adjacent the one ormore layers. In some embodiments, a sealing layer for containment andwaterproofing of the connector element is provided.

In one embodiment, the one or more layers of roofing material have astair-step configuration, for example with the region of greatestthickness positioned so that, when installed, the electrical connectorof an underlying photovoltaic roofing element is disposed adjacent theregion of greatest thickness.

In one embodiment, the one or more layers of roofing material have anotch or recess formed therein, positioned so that, when installed, theelectrical connector of an underlying photovoltaic roofing element isdisposed therein.

One embodiment of the invention is shown in schematic cross-sectionalview in FIG. 24, and in top schematic view in FIG. 25. A photovoltaicroofing element 2400 includes flexible roofing substrate 2410, which inturn includes a base of flexible roofing material 2420, which has topsurface 2422 having a headlap zone 2424 and an exposure zone 2426, and abottom surface 2428; and a layer of shim material 2430 disposed on thetop surface of the base in the headlap zone. The photovoltaic roofingelement 2400 also includes a photovoltaic element 2440 disposed on thetop surface of the base in the exposure zone; an electrical connector2450 disposed on the base and operatively coupled (e.g., through cable2452) to the photovoltaic roofing element; and a shield 2470 disposed onthe top and down-roof surfaces of the electrical connector, as describedabove. The layer of shim material 2430 has a total thickness at leastabout as great as the thickness of the combination of the electricalconnector 2450 and the shield 2470. For example, in the embodiment ofFIGS. 24 and 25, the thickness of the layer of shim material is aboutequal to the thickness of the combination of the electrical connectorand the shield.

In the embodiment of FIGS. 24 and 25, the electrical connector and theshield are shown as sitting entirely on top of the base of flexibleroofing material. In other embodiments, the electrical connector and theshield can be partially embedded in the roofing material, or bepartially disposed in a recess pre-formed therein.

The cable 2452 can be round in cross section, or in certain embodimentscan have a flat cross-section (e.g., a relatively flat ribbon of metalclad in a plastic coating). The person of skill in the art can select aflat cable having sufficient electrical properties for the transmissionof electric power through the photovoltaic system. A flat cable can befolded over so as to lie flat, and can be easily bent to changedirection. Advantageously, the flat cable can lie between photovoltaicroofing elements without causing a protrusion.

FIG. 26 is a cross-sectional schematic view of a photovoltaic roofingsystem 2460, which comprises a plurality of photovoltaic roofingelements 2400 as described above with reference to FIGS. 24 and 25.Overlying courses of photovoltaic roofing elements lay flat on top ofthe shim material, so that the electrical connector and shieldthemselves do not protrude, and are therefore more protected fromdamage. In cases where the shim material is flexible (e.g., when it ismade from flexible roofing material such as that used for the base), theheadlap portion of the can flex to contact the roof (not shown). Thephotovoltaic roofing system can be disposed on a roof deck andinterconnected with an electrical system to form a photovoltaic roofingsystem.

Another embodiment of the invention is shown in side schematiccross-sectional view in FIG. 27, and in top schematic view in FIG. 28. Aphotovoltaic roofing element 2700 includes roofing substrate 2710, whichin turn includes a base of roofing material 2720, which has top surface2722 having a headlap zone 2724 and an exposure zone 2726, and a bottomsurface 2728; and a layer of shim material 2730 disposed on the bottomsurface of the base. The photovoltaic roofing element 2700 also includesa photovoltaic element 2740 disposed on the top surface of the base; anelectrical connector 2750 disposed on the base and operatively coupled(e.g., through cable 2752) to the photovoltaic roofing element; and ashield 2770 disposed on the top and down-roof surfaces of the electricalconnector, as described above. The layer of shim material 2730 (positionshown in dashed line in FIG. 28) has a total thickness at least about asgreat as the thickness of the electrical connector 2750. For example, inthe embodiment of FIGS. 27 and 28, the thickness of the layer of shimmaterial is about equal to the thickness of the electrical connector.Notably, in the embodiments of FIGS. 27-28, the layer of shim materialis positioned so that, when installed, the electrical connector andshield of an underlying photovoltaic roofing element (shown in dottedlines) are disposed adjacent the layer of shim material.

FIG. 29 is a cross-sectional schematic view of a photovoltaic roofingsystem 2960, which comprises a plurality of photovoltaic roofingelements 2700 as described above with reference to FIGS. 27 and 28.Overlying courses of photovoltaic roofing elements lay on top of theshim material, with any bump or protrusion formed by the shim material,so that the electrical connector and shield themselves do not protrude,and are therefore more protected from damage.

The shim material can have a shape that provides a recess (e.g., notchor cut-away) into which the connector and shield can at least partiallyfit. For example, as shown in top schematic view in FIG. 30, aphotovoltaic roofing element 3000 includes flexible roofing substrate,which in turn includes a base of flexible roofing material 3020, whichhas top surface having a headlap zone 3024 and an exposure zone 3026,and a bottom surface (not shown in this view); and a layer of shimmaterial 3030 disposed on the top surface of the base in the headlapzone. The photovoltaic roofing element 3000 also includes a photovoltaicelement 3040 disposed on the top surface of the base in the exposurezone; an electrical connector 3050 disposed on the base and operativelycoupled to the photovoltaic roofing element; and a shield 3070 disposedadjacent the down-roof side of the connector. The layer of shim material3030 has a total thickness at least about as great as the thickness ofthe electrical connector 3050. In the embodiment of FIG. 30, the shimmaterial has cutaways 3032 in which the electrical connectors 3050 andthe shield 3070 are disposed.

The shim material can be any of a variety of materials. For example, inorder to provide for ease of manufacturing in conventional roofingshingle production processes, the shim materials can be layers ofasphalt shingle material. In other embodiments, the shim material can beplastic. The shim material can, for example, include recycled content,such as recycled plastic, recycled asphalt, or other recycled roofingmaterials. Layers of different shim materials can be mixed in a singlephotovoltaic roofing element according to one embodiment of theinvention.

In one embodiment, the one or more layers of shim material have aslanted profile that provides a relatively gradual slope to an overlyingroofing element. For example, as shown in side schematic cross-sectionalview in FIG. 31, a layer of shim material 3130 disposed on top surface3122 of the base of roofing material 3120 is slanted at its end furthestfrom the down-roof edge 3125 of the base of roofing material, so that anoverlying roofing element (shown in dotted outline) can more graduallyslope over the electrical connector 3150 and the shield 3170. Similarly,as shown in side schematic cross-sectional view in FIG. 32, a layer ofshim material 3230 disposed on the bottom surface 3228 of a base ofroofing material 3220 can be slanted at its end furthest from thedown-roof edge 3225 of the base of roofing material, so that the base ofroofing material can more gradually slope over the electrical connector3251 and the shield 3252 of an underlying photovoltaic roofing element(shown in dotted line).

In another embodiment, the one or more layers of shim material have astair-step profile. The stair-step profile can provide a relativelygradual slope as described above with reference FIGS. 31 and 32, and canbe made more simply, for example, using methods used conventionally inthe production of roofing products. In one embodiment, shown inschematic side view in FIG. 33 and in schematic top view in FIG. 34,photovoltaic roofing element 3300 includes roofing substrate 3310, whichin turn includes a base of roofing material 3320, which has top surface3322 having a headlap zone 3324 and an exposure zone 3326, and a bottomsurface 3328. Base 3320 in this embodiment is made of two layers ofroofing material (e.g., reinforced asphalt), a first layer 3320 a thatforms the bottom of the entire photovoltaic roofing element, and asecond layer 3320 b that is formed only in the headlap zone. The roofingsubstrate 3310 further includes a stack 3330 of three layers of shimmaterial 3332, 3334 and 3336 disposed in a stair-step configuration onthe top surface of the base in the headlap zone. The layers 3332, 3334and 3336 have corners cut out to form recesses for electricalconnectors. The photovoltaic roofing element 3300 also includes aphotovoltaic element 3340 disposed on the top surface of the base; anelectrical connector 3350 disposed on the base (here, on the secondlayer 3320 b) and operatively coupled to the photovoltaic roofingelement; and a shield 3370. The stack of shim material 3330 has a totalthickness at least about as great as the thickness of the electricalconnector 3350. For example, in the embodiment of FIGS. 33 and 34, thetotal thickness of the layers of shim material is about equal to thethickness of the combination of the electrical connector and the shield.The electrical connector and the shield are disposed in a cutout regionof the layers of shim material. In such embodiments, the roofingsubstrate and shim materials can be formed from reinforced bituminousmaterials, like conventional (fiber) glass-reinforced or polyester orpolyester/fiber glass composite asphalt materials.

In one embodiment, for example, a photovoltaic roofing element asdescribed above with reference to FIGS. 33 and 34 has an overall height(i.e., distance down the roof from the top of the headlap zone 3324 tothe bottom of the exposure zone 3326) of about 18″. The first layer 3320a of the base has a height of 18″, and the second layer 3320 b has aheight of 9.625″. The three shim layers 3332, 3334, 3336 have heights of7″, 5″ and 3″, respectively.

Similarly, as shown in the photovoltaic roofing element 3500 in FIG. 35,layers of shim material 3532, 3534, 3536 can be disposed in a stair-stepfashion on the bottom surface 3528 of the base 3520 to allow it to moreeasily fit over a connector on an underlying course of photovoltaicelements, as described above. In the embodiment of FIG. 35, the layersof shim material are not flush with the up-roof edge of the base. Ofcourse, in other embodiments, for example as shown in FIG. 36, thelayers of shim material can be flush with the up-roof edge of the base.

In one embodiment the assembly is pre-assembled in a manufacturingenvironment. In another embodiment, the assembly is assembled in thefield, the shingle support having a receptor zone as described in U.S.Provisional Patent Application Ser. No. 61/043,707 filed Apr. 9, 2008,in U.S. Provisional Patent Application Ser. No. 61/014,902 filed Dec.19, 2007 and in U.S. Patent Application Publication no. 2009/0159118,the entirety of each of which is incorporated herein by reference.

Asphalt shingle constructions are known in the shingle art and can beused for the base material. Alternatively, other flexible base materialssuch as elastomeric membrane, polyvinylchloride membrane, thermoplasticpolyolefin membrane or other flexible polymeric materials may be used.The shim materials can be the same as the flexible base materials, ormay be different. When the shim materials are the same as the flexiblebase materials, the roofing substrates can be formed using multi-layershingle production processes familiar to the person of skill in the art.

Another aspect of the invention is a photovoltaic system including aplurality of photovoltaic roofing elements as described above,electrically interconnected. The photovoltaic system (e.g., aphotovoltaic roofing system) can be interconnected with one or moreinverters to allow photovoltaically-generated electrical power to beused on-site, stored in a battery, or introduced to an electrical grid.For example, a single inverter can be used to collect thephotovoltaically-generated power and prepare it for further use. Inother embodiments, the photovoltaic roofing elements can beinterconnected with a plurality of micro-inverters disposed on the roof.For example, a single micro-inverter can be used for each photovoltaicelement or photovoltaic roofing element; or a single micro-inverter canbe used for a group of photovoltaic elements or photovoltaic roofingelements.

In certain embodiments of the invention a plurality of photovoltaicroofing elements are disposed on a roof deck and electricallyinterconnected to form a photovoltaic roofing system. In certainembodiments a shield is provided together with the connector of thephotovoltaic roofing element. In other embodiments, a shield is providedas part of the roofing substrate. In other embodiments, a shield isinstalled separately, for example, after the installation of the roofingsubstrate on the roof, or even after installation and interconnection ofthe photovoltaic elements.

There can be one or more layers of material (e.g. underlayment), betweenthe roof deck and the photovoltaic laminates/roofing elements. The roofcan also include one or more standard roofing elements, for example toprovide weather protection at the edges of the roof, or in areas notsuitable for photovoltaic power generation. In some embodiments,non-photovoltaically-active roofing elements are complementary inappearance or visual aesthetic to the photovoltaic roofing elements.

Any cabling interconnecting the photovoltaic roofing elements of theinvention in a photovoltaic roofing system can, for example, be long andflexible enough to account for natural movement of a roof deck, forexample due to heat, moisture and/or natural expansion/contraction.

It will be understood that power generated by the photovoltaic roofingsystems described herein may be used to power the building itself or maybe directed elsewhere on an electrical grid, as desired. Electricalsystems for handling the photovoltaically-generated power are described,for example, in U.S. Patent Application Publication no. 2008/0271774,which is hereby incorporated herein by reference in its entirety.Photovoltaic elements suitable for use in the present invention aredescribed in, for example, in U.S. Patent Application Publication no.2009/0133340, which is hereby incorporated herein by reference in itsentirety.

Another aspect of the invention is a method for installing aphotovoltaic roofing system comprising disposing on a roof andelectrically interconnecting a plurality of photovoltaic roofingelements as described herein. The disposal on the roof and electricalinterconnections can be performed in any desirable order. In certainembodiments, the photovoltaic roofing elements themselves can beassembled on the roof, for example in conjunction with electricallyinterconnecting them, as described above with reference to U.S. PatentApplication Publication no. 2009/0159118, the entirety of each of whichis incorporated herein by reference.

Another aspect of the invention is a roof comprising a roof deck and aphotovoltaic roofing system as described herein disposed on the roofdeck. The photovoltaic roofing elements described herein can be utilizedwith many different building structures, including residential,commercial and industrial building structures.

Another aspect of the invention is a kit for the installation of aphotovoltaic roofing system, the kit comprising a plurality ofphotovoltaic roofing elements as described herein.

Further, the foregoing description of embodiments of the presentinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. As the person of skill in theart will recognize, many modifications and variations are possible inlight of the above teaching. It will be apparent to those skilled in theart that various modifications and variations can be made to the presentinvention without departing from the scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theclaims and their equivalents.

What is claimed is:
 1. A photovoltaic roofing element comprising aroofing substrate; a photovoltaic element disposed on the roofingsubstrate; an electrical connector operatively connected to thephotovoltaic element, the electrical connector having a top side, adown-roof side and an electrical terminus; and a shield disposedadjacent the electrical terminus of the electrical connector on itsdown-roof side, its top side, or both, wherein the roofing substratecomprises a base of roofing material having a top surface, the topsurface having a headlap zone and an exposure zone, and one or morelayers of shim material disposed on the top surface of the base in theheadlap zone; wherein the electrical connector and the shield aredisposed on the top surface of the base; and wherein the one or morelayers of shim material have a total thickness at least about as greatas the thickness of the combination of the electrical connector and theshield.
 2. The photovoltaic roofing element according to claim 1,wherein the shield is disposed adjacent the electrical terminus of theelectrical connector at least on its down-roof side.
 3. The photovoltaicelement according to claim 2, wherein the terminus of the electricalconnector is oriented laterally.
 4. The photovoltaic roofing elementaccording to claim 1, wherein the shield has a vertical or down-roofpointing flange.
 5. The photovoltaic roofing element according to claim1, wherein the shield is integrally formed with or physically connectedto the electrical connector.
 6. The photovoltaic roofing elementaccording to claim 1, wherein the roofing substrate is flexible.
 7. Thephotovoltaic roofing element according to claim 1, wherein the roofingsubstrate has formed therein a recess shaped to at least partiallyreceive the electrical connector and the shield.
 8. The photovoltaicroofing element according to claim 7, wherein the recess is formed in atop surface of the roofing substrate.
 9. The photovoltaic roofingelement according to claim 7, wherein the recess is formed in a side ofthe roofing substrate.
 10. A photovoltaic roofing system including anelectrically-interconnected plurality of photovoltaic roofing elementsaccording to claim
 1. 11. A roof comprising a roof deck and aphotovoltaic roofing system according to claim 10 disposed on the roofdeck.
 12. A method for installing a photovoltaic roofing system, themethod comprising disposing on a roof deck and electricallyinterconnecting a plurality of photovoltaic roofing elements accordingto claim
 1. 13. The photovoltaic roofing element according to claim 1,wherein the shield has a lateral dimension in the range of about 1 cm toabout 5 cm.
 14. A photovoltaic roofing system including anelectrically-interconnected plurality of photovoltaic roofing elements,the photovoltaic roofing system comprising: a first photovoltaic roofingelement, the first photovoltaic roofing element comprising a roofingsubstrate, a photovoltaic element disposed on the roofing substrate, anelectrical connector operatively connected to the photovoltaic element,the electrical connector having a top side, a down-roof side and anelectrical terminus, and a shield disposed adjacent the electricalterminus of the electrical connector on its down-roof side, its topside, or both; and a second photovoltaic roofing element, the secondphotovoltaic roofing element comprising a roofing substrate; aphotovoltaic element disposed on the roofing substrate; an electricalconnector operatively connected to the photovoltaic element, theelectrical connector having a top side, a down-roof side and anelectrical terminus, wherein the electrical terminus of the electricalconnector of the first photovoltaic roofing element is operativelyengaged with the electrical terminus of the electrical connector of thesecond photovoltaic roofing element, to form an interface therebetween,the interface having a down-roof side and an up-roof side and a top sideand a bottom side, and wherein the shield of the first photovoltaicroofing element extends across the interface and substantially shieldsthe interface on its down-roof side, but not on its up-roof side or itsbottom side.
 15. The photovoltaic roofing system according to claim 14,wherein the terminus of the electrical connector is oriented laterally.16. The photovoltaic roofing system according to claim 14, wherein theshield is integrally formed with or physically connected to theelectrical connector of the first photovoltaic roofing element.